Carbon nanotubes (CNT) are promising candidates for the use as components in nanoscale electronics and electromechanical devices due to their superior mechanical properties, high electron mobility, large current capability, and unique one-dimensional nanostructure. In order to implement these applications, it is essential to develop a simple and reliable manufacturing process that controllably assembles CNT in desired locations with controlled orientations and nanoscale dimensions over a large area.
Previous attempts to assemble CNT into useful structures have utilized chemical vapor deposition (Y. Jung et al., J. Phys. Chem B (2003) 107:6859; K. Hata et al. Science (2004) 306:1362; B. Wei et al., Nature (2002) 416:495; A. Casell et al., J. Phys. Chem. B (1999) 103:6484), chemical functionalization (M. Lee et al., Nat. Nanotech. (2006) 1:66; P. Kamat et al., J. Am. Chem. Soc. (2004) 126:10757), electrophoretic deposition and dielectrophoresis (Lee et al., 2006; P. Makaram et al., Appl. Phys. Lett. (2007) 90:243108(1-3); P. Makaram et al., Nanotechnology (2007) 18:395204(1-5)). Chemical vapor deposition can be used to directly synthesize CNT at desired locations on a substrate by patterning catalyst materials; however, the high temperature of this process (500-900° C.) and difficulty in controlling the growth direction and the density of CNT significantly limits the effectiveness of this method, especially in electronic device applications. Electrophoretic and dielectrophoretic methods can be used to fabricate highly oriented CNT between electrodes, but they are effective only within local areas where the electric field is effective. There remains a need for methods of assembling CNT and other nanoelements over large areas, preferably under ambient conditions.